<?php

if (!defined('BASEPATH'))
  exit('No direct script access allowed');
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 5.1.6 or newer
 *
 * @package		CodeIgniter
 * @author		ExpressionEngine Dev Team
 * @copyright	Copyright (c) 2008 - 2011, EllisLab, Inc.
 * @license		http://codeigniter.com/user_guide/license.html
 * @link		http://codeigniter.com
 * @since		Version 1.0
 * @filesource
 */
// ------------------------------------------------------------------------

/**
 * SQLSRV Database Adapter Class
 *
 * Note: _DB is an extender class that the app controller
 * creates dynamically based on whether the active record
 * class is being used or not.
 *
 * @package		CodeIgniter
 * @subpackage	Drivers
 * @category	Database
 * @author		ExpressionEngine Dev Team
 * @link		http://codeigniter.com/user_guide/database/
 */
class CI_DB_sqlsrv_driver extends CI_DB {

  var $dbdriver = 'sqlsrv';
  // The character used for escaping
  var $_escape_char = '';
  // clause and character used for LIKE escape sequences
  var $_like_escape_str = " ESCAPE '%s' ";
  var $_like_escape_chr = '!';

  /**
   * The syntax to count rows is slightly different across different
   * database engines, so this string appears in each driver and is
   * used for the count_all() and count_all_results() functions.
   */
  var $_count_string = "SELECT COUNT(*) AS ";
  var $_random_keyword = ' ASC'; // not currently supported

  /**
   * Non-persistent database connection
   *
   * @access	private called by the base class
   * @return	resource
   */

  function db_connect($pooling = false) {
    // Check for a UTF-8 charset being passed as CI's default 'utf8'.
    $character_set = (0 === strcasecmp('utf8', $this->char_set)) ? 'UTF-8' : $this->char_set;

    $connection = array(
        'UID' => empty($this->username) ? '' : $this->username,
        'PWD' => empty($this->password) ? '' : $this->password,
        'Database' => $this->database,
        'ConnectionPooling' => $pooling ? 1 : 0,
        'CharacterSet' => $character_set,
        'ReturnDatesAsStrings' => 1
    );

    // If the username and password are both empty, assume this is a 
    // 'Windows Authentication Mode' connection.
    if (empty($connection['UID']) && empty($connection['PWD'])) {
      unset($connection['UID'], $connection['PWD']);
    }

    return sqlsrv_connect($this->hostname, $connection);
  }

  // --------------------------------------------------------------------

  /**
   * Persistent database connection
   *
   * @access	private called by the base class
   * @return	resource
   */
  function db_pconnect() {
    $this->db_connect(TRUE);
  }

  // --------------------------------------------------------------------

  /**
   * Reconnect
   *
   * Keep / reestablish the db connection if no queries have been
   * sent for a length of time exceeding the server's idle timeout
   *
   * @access	public
   * @return	void
   */
  function reconnect() {
    // not implemented in MSSQL
  }

  // --------------------------------------------------------------------

  /**
   * Select the database
   *
   * @access	private called by the base class
   * @return	resource
   */
  function db_select() {
    return $this->_execute('USE ' . $this->database);
  }

  // --------------------------------------------------------------------

  /**
   * Set client character set
   *
   * @access	public
   * @param	string
   * @param	string
   * @return	resource
   */
  function db_set_charset($charset, $collation) {
    // @todo - add support if needed
    return TRUE;
  }

  // --------------------------------------------------------------------

  /**
   * Execute the query
   *
   * @access	private called by the base class
   * @param	string	an SQL query
   * @return	resource
   */
  function _execute($sql) {
    $sql = $this->_prep_query($sql);
    return sqlsrv_query($this->conn_id, $sql, null, array(
        'Scrollable' => SQLSRV_CURSOR_STATIC,
        'SendStreamParamsAtExec' => true
    ));
  }

  // --------------------------------------------------------------------

  /**
   * Prep the query
   *
   * If needed, each database adapter can prep the query string
   *
   * @access	private called by execute()
   * @param	string	an SQL query
   * @return	string
   */
  function _prep_query($sql) {
    return $sql;
  }

  // --------------------------------------------------------------------

  /**
   * Begin Transaction
   *
   * @access	public
   * @return	bool
   */
  function trans_begin($test_mode = FALSE) {
    if (!$this->trans_enabled) {
      return TRUE;
    }

    // When transactions are nested we only begin/commit/rollback the outermost ones
    if ($this->_trans_depth > 0) {
      return TRUE;
    }

    // Reset the transaction failure flag.
    // If the $test_mode flag is set to TRUE transactions will be rolled back
    // even if the queries produce a successful result.
    $this->_trans_failure = ($test_mode === TRUE) ? TRUE : FALSE;

    return sqlsrv_begin_transaction($this->conn_id);
  }

  // --------------------------------------------------------------------

  /**
   * Commit Transaction
   *
   * @access	public
   * @return	bool
   */
  function trans_commit() {
    if (!$this->trans_enabled) {
      return TRUE;
    }

    // When transactions are nested we only begin/commit/rollback the outermost ones
    if ($this->_trans_depth > 0) {
      return TRUE;
    }

    return sqlsrv_commit($this->conn_id);
  }

  // --------------------------------------------------------------------

  /**
   * Rollback Transaction
   *
   * @access	public
   * @return	bool
   */
  function trans_rollback() {
    if (!$this->trans_enabled) {
      return TRUE;
    }

    // When transactions are nested we only begin/commit/rollback the outermost ones
    if ($this->_trans_depth > 0) {
      return TRUE;
    }

    return sqlsrv_rollback($this->conn_id);
  }

  // --------------------------------------------------------------------

  /**
   * Escape String
   *
   * @access	public
   * @param	string
   * @param	bool	whether or not the string will be used in a LIKE condition
   * @return	string
   */
  function escape_str($str, $like = FALSE) {
    // Escape single quotes
    return str_replace("'", "''", $str);
  }

  // --------------------------------------------------------------------

  /**
   * Affected Rows
   *
   * @access	public
   * @return	integer
   */
  function affected_rows() {
    return @sqlrv_rows_affected($this->conn_id);
  }

  // --------------------------------------------------------------------

  /**
   * Insert ID
   *
   * Returns the last id created in the Identity column.
   *
   * @access public
   * @return integer
   */
  function insert_id() {
    return $this->query('select @@IDENTITY as insert_id')->row('insert_id');
  }

  // --------------------------------------------------------------------

  /**
   * Parse major version
   *
   * Grabs the major version number from the
   * database server version string passed in.
   *
   * @access private
   * @param string $version
   * @return int16 major version number
   */
  function _parse_major_version($version) {
    preg_match('/([0-9]+)\.([0-9]+)\.([0-9]+)/', $version, $ver_info);
    return $ver_info[1]; // return the major version b/c that's all we're interested in.
  }

  // --------------------------------------------------------------------

  /**
   * Version number query string
   *
   * @access public
   * @return string
   */
  function _version() {
    $info = sqlsrv_server_info($this->conn_id);
    return sprintf("select '%s' as ver", $info['SQLServerVersion']);
  }

  // --------------------------------------------------------------------

  /**
   * "Count All" query
   *
   * Generates a platform-specific query string that counts all records in
   * the specified database
   *
   * @access	public
   * @param	string
   * @return	string
   */
  function count_all($table = '') {
    if ($table == '')
      return '0';

    $query = $this->query("SELECT COUNT(*) AS numrows FROM " . $this->dbprefix . $table);

    if ($query->num_rows() == 0)
      return '0';

    $row = $query->row();
    $this->_reset_select();
    return $row->numrows;
  }

  // --------------------------------------------------------------------

  /**
   * List table query
   *
   * Generates a platform-specific query string so that the table names can be fetched
   *
   * @access	private
   * @param	boolean
   * @return	string
   */
  function _list_tables($prefix_limit = FALSE) {
    return "SELECT name FROM sysobjects WHERE type = 'U' ORDER BY name";
  }

  // --------------------------------------------------------------------

  /**
   * List column query
   *
   * Generates a platform-specific query string so that the column names can be fetched
   *
   * @access	private
   * @param	string	the table name
   * @return	string
   */
  function _list_columns($table = '') {
    return "SELECT * FROM INFORMATION_SCHEMA.Columns WHERE TABLE_NAME = '" . $this->_escape_table($table) . "'";
  }

  // --------------------------------------------------------------------

  /**
   * Field data query
   *
   * Generates a platform-specific query so that the column data can be retrieved
   *
   * @access	public
   * @param	string	the table name
   * @return	object
   */
  function _field_data($table) {
    return "SELECT TOP 1 * FROM " . $this->_escape_table($table);
  }

  // --------------------------------------------------------------------

  /**
   * The error message string
   *
   * @access	private
   * @return	string
   */
  function _error_message() {
    $error = array_shift(sqlsrv_errors());
    return !empty($error['message']) ? $error['message'] : null;
  }

  // --------------------------------------------------------------------

  /**
   * The error message number
   *
   * @access	private
   * @return	integer
   */
  function _error_number() {
    $error = array_shift(sqlsrv_errors());
    return isset($error['SQLSTATE']) ? $error['SQLSTATE'] : null;
  }

  // --------------------------------------------------------------------

  /**
   * Escape Table Name
   *
   * This function adds backticks if the table name has a period
   * in it. Some DBs will get cranky unless periods are escaped
   *
   * @access	private
   * @param	string	the table name
   * @return	string
   */
  function _escape_table($table) {
    return $table;
  }

  /**
   * Escape the SQL Identifiers
   *
   * This function escapes column and table names
   *
   * @access	private
   * @param	string
   * @return	string
   */
  function _escape_identifiers($item) {
    return $item;
  }

  // --------------------------------------------------------------------

  /**
   * From Tables
   *
   * This function implicitly groups FROM tables so there is no confusion
   * about operator precedence in harmony with SQL standards
   *
   * @access	public
   * @param	type
   * @return	type
   */
  function _from_tables($tables) {
    if (!is_array($tables)) {
      $tables = array($tables);
    }

    return implode(', ', $tables);
  }

  // --------------------------------------------------------------------

  /**
   * Insert statement
   *
   * Generates a platform-specific insert string from the supplied data
   *
   * @access	public
   * @param	string	the table name
   * @param	array	the insert keys
   * @param	array	the insert values
   * @return	string
   */
  function _insert($table, $keys, $values) {
    return "INSERT INTO " . $this->_escape_table($table) . " (" . implode(', ', $keys) . ") VALUES (" . implode(', ', $values) . ")";
  }

  // --------------------------------------------------------------------

  /**
   * Update statement
   *
   * Generates a platform-specific update string from the supplied data
   *
   * @access	public
   * @param	string	the table name
   * @param	array	the update data
   * @param	array	the where clause
   * @param	array	the orderby clause
   * @param	array	the limit clause
   * @return	string
   */
  function _update($table, $values, $where) {
    foreach ($values as $key => $val) {
      $valstr[] = $key . " = " . $val;
    }

    return "UPDATE " . $this->_escape_table($table) . " SET " . implode(', ', $valstr) . " WHERE " . implode(" ", $where);
  }

  // --------------------------------------------------------------------

  /**
   * Truncate statement
   *
   * Generates a platform-specific truncate string from the supplied data
   * If the database does not support the truncate() command
   * This function maps to "DELETE FROM table"
   *
   * @access	public
   * @param	string	the table name
   * @return	string
   */
  function _truncate($table) {
    return "TRUNCATE " . $table;
  }

  // --------------------------------------------------------------------

  /**
   * Delete statement
   *
   * Generates a platform-specific delete string from the supplied data
   *
   * @access	public
   * @param	string	the table name
   * @param	array	the where clause
   * @param	string	the limit clause
   * @return	string
   */
  function _delete($table, $where) {
    return "DELETE FROM " . $this->_escape_table($table) . " WHERE " . implode(" ", $where);
  }

  // --------------------------------------------------------------------

  /**
   * Limit string
   *
   * Generates a platform-specific LIMIT clause
   *
   * @access	public
   * @param	string	the sql query string
   * @param	integer	the number of rows to limit the query to
   * @param	integer	the offset value
   * @return	string
   */
  function _limit($sql, $limit, $offset) {
    $i = $limit + $offset;

    return preg_replace('/(^\SELECT (DISTINCT)?)/i', '\\1 TOP ' . $i . ' ', $sql);
  }

  // --------------------------------------------------------------------

  /**
   * Close DB Connection
   *
   * @access	public
   * @param	resource
   * @return	void
   */
  function _close($conn_id) {
    @sqlsrv_close($conn_id);
  }

}

/* End of file mssql_driver.php */
/* Location: ./system/database/drivers/mssql/mssql_driver.php */